TORONTO — Major League Baseball's new rule on home plate collisions is causing some confusion.

Houston Astros manager Bo Porter had a telephone conversation Wednesday with Hall of Fame manager Tony La Russa, currently a special assistant to baseball commissioner Bud Selig. Porter said La Russa told him the league intends to clarify its rule on blocking the plate, and how such calls are challenged and reviewed.

"My understanding is there will be a memo coming out that will bring some more clarity to it," Porter said before the Astros played the Blue Jays on Wednesday night.